Flat Roofing Systems Overview

Flat roofing systems come in many different types, colors, and thicknesses. But what is the difference between them? The 5 most common types of roof systems are below. Click on the tabs to get more information on each system.

 

TPO (Thermoplastic PolyOlefin)

Finished TPO Complex

Years Used as Roofing ProductOver 30 Years
Base ProductPolyolefins (Polypropylene,Polyethylene) / Plastics
ColorWhite, Gray, Tan + Pallet of colors over 100,000 Square Feet
Temperature Impact on RoofCools Roof
Seaming technologyHeat Welded
Thicknesses.045 to .080
ReinforcedAlways Reinforced
Puncture ResistanceGood to excellent, depending on thickness
Chemical ResistanceGood
Environmental ImpactExcellent
Slippery With MoistureYes
Known ProblemsEffective welding requires experience.

EPDM “Rubber” (Ethylene Propylene Diene Monomer)

EPDM Membrane CoverPhoto

Years Used as Roofing ProductOver 50 Years
Base ProductSynthetic Rubber
ColorBlack, White (At price premium)
Temperature Impact on RoofHeats roof (Unless white)
Seaming technologySince 1980, 3” or 6” Seam Tape.
Before 1980, liquid adhesives
Thicknesses.045 to .090
ReinforcedReinforced or Non-Reinforced
Puncture ResistanceGood to excellent, depending on thickness
Chemical ResistancePoor
Environmental ImpactModerate
Slippery With MoistureYes – Moderate
Known Problems
  • Seams come apart over time.
  • Grease and other chemicals deteriorate product.
  • Creates hot environments for rooftop equipment.

PVC “Vinyl” (Polyvinyl Chloride)

PVC Coverphoto

Years Used as Roofing ProductOver 50 Years, but formula has changed dramatically over time
Base ProductVinyl / Plastics
ColorWhite, Gray, Tan
Temperature Impact on RoofCools Roof
Seaming technologyHeat Welded, with earlier systems using solvent welded seams
Thicknesses.036 to .090
ReinforcedAlways Reinforced (Older non-reinforced systems could shatter)
Puncture ResistanceOK to Good, depending on thickness and manufacturer
Chemical ResistanceExcellent
Environmental ImpactPoor – is actually banned in some countries
Slippery With MoistureYes -Very
Known Problems
  • Older products shattered under colder conditions.
  • Newer products still shatter, but reinforcement contains it to smaller areas.
  • Shrinks over time causing numerous issues.
  • Expensive compared to other single ply products.
  • Many concerns with fire resistance and fumes emitted when burned.
  • Effective welding requires experience.

Modified Bitumen (Mod-Bit)

Completed Modified

Years Used as Roofing ProductOver 50 Years
Base ProductAsphalt with modifiers (APP and SBS)
ColorWide variety of colors readily available
Temperature Impact on RoofDependent on color used
Seaming technologyDepends on Installation Method. Typically adhered with hot asphalt or cold adhesives.
Thicknesses2-5 plys
ReinforcedN/A
Puncture ResistanceOutstanding
Chemical ResistanceGood
Environmental ImpactModerate
Slippery With MoistureNo
Known Problems
  • Very Expensive
  • Cracks and pulls apart without granules or other protection from sun
  • Some application methods, like torch down, are extremely hazardous and unsafe

 

Built Up Roof (BUR)

BUR Roof Overview

Years Used as Roofing ProductOver 150 Years
Base ProductAsphalt or Coal Tar Pitch
ColorBlack, Often Graveled
Temperature Impact on RoofHeats Roof
Seaming technologyMopped down with hot asphalt
Thicknesses2-5 plys
ReinforcedN/A
Puncture ResistanceOutstanding
Chemical ResistanceGood
Environmental ImpactModerate
Slippery With MoistureNo
Known Problems
  • Incredibly high cost
  • Cracks and pulls apart without protection from sun
  • Mopped down installation method is very unsafe
  • Asphalt products don’t last as long as they used to